The present invention relates to fuel pumps for gasoline direct injection (GDI) engines.
Engine manufacturers use both port injection (PI) and direct injection (DI) fuel systems concurrently on some engines as a strategy to improve emissions results. PI and DI are used individually or simultaneously depending on engine operating regimes. Very high DI supply pressure is desired for achieving high quality of the injection.
The PI system relies on the pressure of the low-pressure feed pump (LPP), typically installed in the fuel tank. The same LPP feeds the inlet pressure of the high pressure pump (HPP) pump, a separate pump installed in the engine bay for use in the DI system. The LPP's are known for efficiency and durability, but over time suffer reduction in maximum delivery pressure.